Process for producing speckled fabric



Oct. 19, 1965 R. A. KASEY, JR

PROCESS FOR PRODUCING SPECKLED FABRIC Original Filed Jan. 19, 1959INVENTOR ROBERT A. KASEY, JR.

United States Patent 4 Claims. (Cl. 28-74) This application is acontinuation-in-part of my application Serial No. 607,499 filed August31, 1956, now abandoned, and is a divisional application of my copendingapplication Serial No. 787,774 filed January 19, 1959, now-U.S. Patent3,116,197.

This invention relates to the production of novel continuous filamentsmade from linear condensation polyesters. More specifically, it concernsnovel yarns of terephthalate polyesters which exhibit a dry, crepe-likehand when woven or knitted into fabrics and subjected to a mild heattreatment.

Polyethylene terephthalate, a well-known example of a linearterephthalate polyester, has achieved considerable commercial importancein the form of continuous filament textile yarns owing to its hightenacity, low moisture absorption, resistance to chemical attack, andother desirable properties. However, one characteristic of continuousfilament polyethylene terephthalate fabrics which has prevented fullacceptance of these fabrics for certain textile uses is their smooth,almost slippery tactile sensation, or hand. The hand of continousfilament polyethylene terephthalate fabrics prepared from yarns ofuniform denier is usually characterized as cool and slick. Fabricsprepared from continuous filament yarns of other linear terephthalatepolyesters, such as poly(trans-p-hexahydroxylylene terephthalate),display a similar cool and slick hand.

Continuous filament linear terephthalate polyester yarns are usuallyprepared by extruding the desired number of streams of the moltenpolymer through a spinneret and winding up the bundle of solidifiedunoriented filaments into a yarn package, following which the yarn isoriented by drawing it to several times its original length. Preferablythe drawing step is facilitated -by heating the yarn to about 90-115 C.during the drawing step. Under certain conditions, the drawing step maybe carried out in a manner to produce a drawn yarn containing randompatches of thick, unoriented yarn, most of the patches being about aninch in length or longer when the amount of unoriented yarn constitutesmore than about 1% of the total length of yarn. Continuous filamentfabrics prepared from such yarn are found to have a slightly drier handthan fabrics prepared from uniformly oriented yarn, but the hand isstill essentially smooth and the fabrics lack the desired crepe-likesurface character.

It is an object of this invention to provide novel continuous filamentlinear terephthalate polyester yarns. A further object is to providefabrics which have a dry, crepe-like hand from such yarns. Other objectswill be apparent from the following description.

These objects are realized by the present invention, which comprehends acontinuous filament linear terephthalate polyester yarn characterized bysharply defined alternate smaller and larger denier segments. In apreferred embodiment of the invention, the smaller denier segments areof substantially crystalline structure, and the larger denier segmentsare substantially amorphous. Woven and knitted fabrics having adesirable dry-crepelike hand may be prepared from the novelthick-and-thin yarns of this invention. Such fabrics, when dyed, have anovel speckled appearance which is very appealing.

3,212,158 Patented Oct. 19, 1965 The speckled appearance is especiallyapparent when the fabrics are not subjected to heat prior to the dyeingstep and when a light shade of dye is used.

By linear terephthalate polyester is meant a linear condensationpolyester comprising recurring glycol dicarboxylate structural units inwhich at least about of the recurring structural units are units of theformula wherein G represents a divalent organic radical containing from2 to about 18 carbon atoms which is attached to the adjacent oxygenatoms by saturated carbon atoms. Preferably, the radical G contains from2 to about 10 carbon atoms. The terephthalate radical may be the soledicarboxylate constituent of the recurring structural units, or up toabout 25% of the recurring structural units may contain otherdicarboxylate radicals, such as the adipate, sabacate, isophthalate,bibenzo'ate, hexahydroterephthal-ate, diphenoxyethane-4,4-dicarboxylate, p,p'-carboxyldibenzoate, and p,p'-sulfonyldibenzoateradicals.

FIGURE 1 is a diagrammatic illustration of apparatus useful in preparingthe novel filaments and yarns of this invention;

FIGURE 2 is an illustration of novel linear terephthalate polyesterfilaments prepared according to the present invention, greatly enlarged;and

FIGURE 3 is an end elevation of the upper half of a roll equipped withvanes which may be used in preparing the novel yarns of this invention.

Referring now to FIGURE 1, substantially amorphous, unoriented linearterephthalate polyester yarn 1 is passed from a'source of supply (notshown) under a guide pin 2, between feed rolls 3 and 4, around heatedgrooved roll 5, and finally around draw roll 6. The rolls rotate onshafts 7 in the direction shown by the arrows, rolls 3, 4, and 5rotating at the same uniform peripheral speed and roll 6 rotating at ahigher peripheral speed, preferably about 2 to 4 times the peripheralspeed of rolls 3, 4, and 5. After leaving roll 6, the yarn is wound upin any suitable manner. Rolls 3, 4, and 6 are unheated, while groovedroll 5 is heated to a suitable temperature, usually about to 115 C. Feedrolls 3 and 4 are usually mounted to operate in contact, while roll 5 isslightly separated from the feed roll; however, this arrangement is notcritical, and any suitable system which imparts some slight tension tothe running yarn ahead of the grooved roll may be used.

The linear terephthalate polyester yarn is passed around the heatedgrooved roll 5, usually about one full turn, during which time thoseportions of the yarn which contact the raised areas 8 of the heated rollbecome heated. The heated portions of the yarns are drawn as they leavethe grooved roll because of the tension exerted by draw roll 6, becomingsubstantially oriented and crystalline; however, portions of the yarnwhich have passed around the roll above the longitudinal grooves 9 ofthe roll are unheated and remain substantially undrawn, providingsharply defined sections of the yarn which are still substantiallyunoriented and substantially amorphous.

FIGURE 2 represents a magnified view (about x) of a portion of threefilaments from a continuous filament linear terephthalate polyester yarnof this invention, segments 10 being substantially oriented andsubstantially crystalline and segments 11 of substantially greaterdiameter being relatively unoriented and relatively amorphous. As shownin the figure, the transition points 12 between the oriented,crystalline segments and the unoriented, amorphous segments are abrupt.A yarn bundle usually contains from about 10 to about 100 of thesefilaments, which tend to remain associated together in the samelongitudinal relationship prevailing in the drawing step, i.e., theunoriented yarn segments tend to remain grouped together in the yarnbundle, as indicated in the drawmg.

Shallow longitudinal grooves 9 may be formed in a solid roll, ifdesired, by any suitable known means. The grooves are made approximatelythe same width as the desired length of the unoriented segments in theyarn to be made with the roll; however, the distance between grooves onthe surface of the roll is considerably less than the desired length ofthe oriented segments of the yarn to be made with the roll, since theoriented segments are formed by drawing the heated portions of yarn asthey leave the roll. Usually the separation between grooves is about 30to 40% of the desired length of the oriented sections, depending on thedrawing conditions to be used.

Instead of forming grooves in a solid roll, the grooved roll may beconstructed as shown in FIGURE 3. The body 13 of the roll is a rightcylinder having a regular polygonal surface 14 of as many sides as thenumber of grooves desired. Vanes 15 atfixed to the body of the roll aresubstantially rectangular in cross section, having a slightly arcuatesurface 16 suchthat all of the vanes together provide a circular surfaceinterrupted by grooves 17 which constitute the spaces separating thevanes. The vanes are preferably affixed to the body by bolts 18,although other suitable means of attachment may be employed. The rollalso has central bore 19 for the shaft and well 20 into which cartridgeheaters or other suitable heating means may be inserted. Alternatively,the roll may be adapted to rotate about and in close contact with astationary heater block containing suitable heating means.

The novel yarns of this invention are characterized by sharply definedalternate smaller and larger denier segments. The smaller deniersegments range in length from about 0.1 to about 1.5 inches, and thelarger denier segments range in length from about 0.015 to about 0.15inch, with the smaller denier segments always being longer than thelarger denier segments. Larger denier segments more than about 0.15 inchin length are to be avoided since much of the crepe-like texture andspecked appearance of fabrics prepared from the yarns of this inventionis dependent upon substantially unoriented segments which are shorterthan about 0.15 inch. Larger denier segments less than about 0.015 inchin length are difiicult to obtain in a uniform way, while yarns in whichthe smaller denier segments are substantially less than about 0.1 inchin length are also ditficult to prepare. On the other hand, when thesmaller denier segments exceed about 1.5 inches in length, fabric handbecomes progressively more smooth and slick and approaches the fabrichand prepared from uniformly oriented terephthalate yarn.

For convenience in manufacture, the lengths of both the oriented andunoriented segments are usually constant along the length of thefilament. However, if desided, the length of either or both may bevaried. Fabrics prepared from yarns having oriented and unorientedsegments of varying lengths, within the previously defined limits,generally have a hand and appearance similar to fabrics prepared fromyarns in which the lengths of each type of segment are constant.

Yarns of this invention are further characterized in that the smallerdenier segments are substantially oriented and crystalline, whereas thelarger denier segments are substantially unoriented and amorphous. Byheating these filaments or yarns, however, they may be converted intostructures having even more pronounced intrafilament denier variationbut in which both smaller and larger denier segments are substantiallycrystalline in structure. Heating at a temperature of about 90 C. orabove in water, or with dry heat between about 125 C. and about 200 C.,is suitable for this purpose. Usually, heating for about minutes inwater at 90 C. will be sufficient to convert substantially amorphoussegments of the filament or yarn to a crystalline structure, and athigher temperatures shorter periods of heating are suflicient. At about200 C. only a few seconds heating time is necessary. Usually it isdesirable to weave or knit the yarn into a fabric prior to heating.

Heating of the novel thick-and-thin yarns of this invention at atemperature between about C. and about 200 C. for from about 30 minutesto about 10 seconds results in non-uniform shrinkage of the yarn, andnaturally this shrinkage takes place also if the yarn is in fabric form.The thick or larger denier segments shrink at least 15% more than do thethin or smaller denier segments of the yarn during the heating, and alsoundergo a correspondingly larger increase in denier. For example, if thethin sections shrink 25% during the heat treatment, the thick sectionswill shrink at least 40%. Actual shrinkage values may be varied overwide limits depending upon the characteristics of the spun yarn, thedraw ratio, and the temperature of the vanes of the draw rolls.

Surprisingly, when fabrics prepared from the novel yarns of thisinvention are subjected to this heat treatment, the hand of the fabricundergoes a marked change from cool and slick to crepe-like.

The thick-and-thin portions of the novel yarn of this invention differsubstantially with respect to birefringence, a measure of the degree oforientation of the yarn. Prior to heat treatment, the thick portions ofthe yarn are characterized by the birefringence of between about 0.0002and about 0.030, whereas the birefringence of the thin portions isgreater than about 0.1. The ratio of the diameter of the thick portionsto the thin portions may vary between about 1.3 and about 2.0 prior toheat treatment (shrinkage); after heat treatment, the ratio will varyfrom about 1.4 to about 2.7.

Fabrics may be prepared by knitting or weaving the yarns of thisinvention; preferably, the fabrics are prepared before the yarns havebeen subjected to heat treatment (shrinkage). Fabrics prepared fromthese yarns and then heat-treated at a temperature above 90 C. inaccordance with this invention exhibit a dry crepelike hand, and, upondyeing, are characterized by a desirable novel speckled appearance. Afabric having a particularly enhanced speckled appearance is producedwhen a fabric prepared from yarn of this invention is dyed at atemperature of at least 90 C. prior to any heat treatment of the yarn orfabric above that temperature. Such fabrics also exhibit a drycrepe-like hand.

The following examples are illustrative of novel linear terephthalatepolyester yarns provided by the present invention and the process forpreparing them.

Example 1 Apparatus for drawing yarn is set up as shown in FIG- URE 1,the grooved roll being a roll of the type shown in FIGURE 3. The body ofthe roll, originally a right circular cylindrical aluminum roll 4%inches in diameter and 2 inches wide, is machined to convert thecircular surface of the roll into 36 flat sides of equal width.Thirty-six brass vanes extending the width of the roll and having thedimensions of inch (width) x 7 inch (height) are attached to the roll'by fiat head screws. The surface of the roll is then ground down sothat the faces of the vanes comprise a smooth circular surface about 4.5inches in diameter interrupted by the grooves afforded by the spacingsbetween the vanes, which measure about 0.04 inch in width at the surfaceof the roll. The outer surfaces of the vanes are then polished andchromiumplated. Means for heating the roll consist of three 50- wattcartridge heaters mounted in a stationary heater block about which theroll rotates, the clearance being /52 inch.

Polyethylene terephthalate polymer, having an intrinsic viscosity of0.63, is extruded at 275 C. through a spinneret into air, and the yarnis wound up at the rate of 1206 yards per minute. The yarn, comprising27 filaments having a total undrawn denier of 135, has a birefringenceof 0.0090. In drawing the yarn in the apparatus described above, thefeed rolls and the grooved roll are operated to give a yarn speed of 141yards per minute, and the yarn is passed around the draw roll at 375yards per minute. The grooved roll is maintained at 108 C. The drawnyarn, when examined under magnification, has the novel appearancedepicted in FIGURE 2. The thick portions of the yarn are about 0.07 inchin length and have a diameter approximately 1.7 times that of theintervening smaller denier segments, which are about 0.9 inch in length.

A ten-inch length of the drawn yarn is placed under a microscope and thelength of each of the thick segments of yarn is measured to the nearest0.005 inch. The yarn is then placed in boiling water for one minute,after which the yarn is found to have undergone an rover-all shrinkageof The yarn is then placed under a microscope again .and the new lengthsof the thick segments of yarn are measured. When the original and finallengths of the thick segments are compared, it is found that the thicksegments have shrunk 49%. The shrinkage of the thin segments is thencalculated by difference as 12.5%.

Analysis of X-ray diffraction patterns of the yarn segments indicatesthat the thick portions of the filaments are substantially amorphous,while the thin segments are substantially crystalline in character.Thick portions of the filaments exhibit a birefringence of 0.0092,essentially the same as the undrawn yarn, while thin segments have abirefringence of 0.2510, indicating a high degree of orientation.Birefringence, or double refraction, of polyethylene terephahalatefilaments is measured by the retardation technique described in ModernTextile Microscopy by J. M. Preston (London, 1933) page 270, using apetrographic microscope (such as the Bausch & Lomb Model LB) togetherwith a cap analyzer compensator (Ban-sch & Lomb Style B).

Yarn prepared as described above is knit into a twobar Jersey tricotfabric (12 inches per rack). Prior to finishing, the fabric has arelatively smooth, slick hand quite similar to a corresponding fabricprepared from conventional polyethylene terephthalate yarn. A strikingtransformation in the hand of the fabric is achieved, however, byscouring the fabric at the boil for 30 minutes, the scoured fabrichaving an appealing dry, crepe-like hand. Analyses of X-ray diffractionpatterns of the yarn in the scoured fabric indicates that both thickportions and thin portions of the yarn are substantially crystalline.

The fabric is then bleached at 185 F. for 30 minutes with a solutioncontaining 2 grams per liter each of so dium chl-orite and nitric acid,followed by dyeing at the boil with /2% (based on fabric weight) ofLatyl Brilliant Blue BG dye (listed on page 2 of the 1955 TechnicalManual and Year Book of the American Association of Textile Chemists andColorists, vol XXXI). The dyed fabric has a novel speckled, pebblyappearance, the color being a medium shade of blue. The finishingtreatments are completed with a heat setting step at 430 F. for seconds.The final fabric is characterized both by its dry, crepe-like hand andits novel speckled appearance.

In a similar experiment the tricot fabric is scoured at 60 C., which isinsufiicient to develop the dry, crepelike hand. The fabric is then dyedat the boil, which not only develops the dry, crepe-like hand but alsoprovides a greater contrast in the speckled appearance of the fabricthan has been achieved previously by scouring the fabric at the boilprior to dyeing.

A two-bar Jersey tricot fabric in which the novel polyethyleneterephthalate yarn is used in the top bar and 10- filament, 30-deniernylon yarn is used in the bottom bar exhibits a relatively dry,crepe-like hand after heating at 100 0, although the effect is lessmarked than when the fabric is constructed entirely of the novelpolyethylene terephthalate yarn. A filling-face satin fabric woven fromthe novel polyethylene terephthalate yarn also exhibits an appealingdry, crepe-like hand and has an attractive speckled appearance whendyed.

Polyethylene terephthalate yarn is spun as above described but drawnover a hot pin 1.6 inches in diameter maintained at C. with a rate offeed of 151 yards per minute and a rate of withdrawal of 545 yards perminute. The uniformly drawn yarn is knitted into a two-bar Jersey tricotfabric (12 inches per rack). The smooth, slick, cool hand of the fabricis substantially unaltered by scouring at the boil. When bleached anddyed under the same conditions described in Example I, the fabric dyesto a level, uniform shade of blue.

Example II A roll having a construction similar to that described inExample I is fabricated, except that 72 vanes each 0.16 inch in widthare used, the spacings between vanes measuring about 0.04 inch in widthat the surface of the roll. Polyethylene terephthate yarn prepared asdescribed in Example I, comprising 34 filaments having a total undrawndenier of 135, is passed around the grooved roll at 153 yards per minuteand around the draw roll at 375 yards per minute. The grooved roll ismaintained at C. The thick sections of the yarn, which are about 0.05inch in length, are about 1.6 times the diameter of the interveningsegments, which are about 0.38 inch in length. Tricot fabric prepared,finished and dyed as described in Example I, exhibits a notably dry,crepe-like hand and a highly speckled appearance.

Example III Undrawn yarn of poly(trans-p-hexahydroxylyleneterephthalate) consisting of 27 filaments and having a total denier ofis drawn as described in Example I with the exception that the heatedgrooved roll is maintained at a temperature of 112 C. The drawn yarn,when examined under magnification, has the novel appearance depicted inFIGURE 2. The thick portions of the yarn are about 0.06 inch in lengthand have a diameter approximately 1.6 times that of the interveningsmaller denier segments, which are about 0.9 inch in length.

Yarn prepared as described above is knit into a twobar Jersey tricotfabric. Prior to finishing, the fabric has a relatively smooth, slickhand similar to a corresponding fabric prepared from conventionalterephthalate polyester yarns. A striking transformation in the hand ofthe fabric is observed, however, by scouring the fabric at the boil for30 minutes, the scoured fabric having an appealing, dry, crepe-likehand.

The fabric is then dyed a light blue color as in EX- ample I and isfound to have a novel speckled pebbly appearance.

Example IV Undrawn yarn of polyethylene terephthalate/S-(sodiumsulfo)isophthalate (98/2) consisting of 34 filaments and having a totaldenier of 135 is drawn as described in Example II with the exceptionthat the heated groove roll is maintained at a temperature of 105 C.When examined under magnification, the drawn yarn is found to have thicksections about 0.05 inch in length and thin sections about 0.4 inch inlength. Tricot fabrics prepared from this yarn, finished as in ExampleI, and dyed at the boil to a medium violet shade with1,4-diamino-2,3-dichloroanthraquinone, is found to have a remarkably drycrepe-like hand and a highly speckled appearance.

The linear terephthalate polyesters suitable for the purposes of thepresent invention may be prepared by reacting terephthalic acid or amixture of terephthalic acid and one or more other dicarboxylic acidswith a glycol, G(OH) where G is a radical as defined above, to form thebis-glycol ester or mixture of esters, followed by polycondensation atelevated temperature and reduced pressure with elimination of excessglycol. In place of the acid or acids, ester-forming derivatives may beused, i.e., derivatives which readily undergo polyesterification with aglycol or derivative thereof. For example, the acid chloride or a loweralkyl ester, such as the dimethyl ester, may be used. Similarly, anester-forming derivative of the glycol may be used in place of theglycol; i.e., a derivative of the glycol which readily undergoespolyesterification with dicarboxylic acids or derivatives thereof. Forexample, a cyclic oxide from which the corresponding glycol can bederived by hydrolysis may be used.

The glycol G(OH) from which the polyester is prepared may be anysuitable dihydroxy compound containing from 2 to 18 carbon atoms,preferably from 2 to carbon atoms, in which the hydroxyl groups areattached to saturated carbon atoms. Thus, the radical -G may be of theform (C H Y where n and p are positive integers and Y is acycloaliphatic group, an aromatic group, an oxy group, or anarylenedioxy group. Examples of suitable glycols where p=1 include thepolymethylene glycols, such as ethylene glycol, tetramethylene glycol,hexamethylene glycol, and decamethylene glycol as well as the branchedchain glycols such as 2,2-dimethyl-1,3-propanediol and2,2-dimethyl-1,4-butanediol. Suitable glycols in which p=2 includetrans-p-hexahydroxylylene glycol, bis-p-(Z-hydroxyethyl)benzene,diethylene glycol, bis-(4-hydroxybutyl)ether, bis p(,8hydroxyethoxy)benzene, bis-1,4- (B-hydroxyethoxy) 2,5dichlorobenzene, bis-4,4-(fi-hydroxyethoxy)diphenyl,2,6-di(/3-hydroxyethoxy)naphthalene,bis-[p-(B-hydroxyethoxy)phenyl]ketone, bis[p-(fihydroxyethoxy)phenyl]sulfone, and bis[p (flhydroxyethoxy)phenyl]difluoromethane. Glycols in which p=3 include 4,4bis (,B hydroxyethyl)biphenyl, 4,4 bis-(fi-hydroxyethyl)dodecahydrobiphenyl, triethylene glycol, and 2,2(ethylenedioxybis-[p-phenyleneoxy] )diethanol. In general, the glycolsin which p is greater than 3 are of lesser interest, although certainglycols such as tetraethylene glycol may be used. A preferred class ofglycols for use in preparing the terephthalate polyesters are thoseselected from the series HO(CH OH where m is an integer from 2-10.Mixtures of the glycols may be used. If desired small amounts, e.g., upto about weight percent, of a higher glycol such as a polyethyleneglycol of high molecular weight may be added.

What is claimed is:

1. A process comprising heating alternate sections of an undrawnpolyethylene terephthalate continuous filament at a temperature betweenabout C. and about C., drawing the non-uniformly heated filament toproduce a filament characterized by sharply defined alternate smallerand larger denier segments, the smaller denier segments ranging inlength from about 0.1 to about 1.5 inches, and the larger deniersegments ranging in length from about 0.015 to about 0.15 inch,incorporating such filaments into a fabric, heating the fabric at atemperature between about 90 C. and about 200 C. for between about 30minutes and about 10 seconds and dyeing the fabric, thereby imparting toit a novel, speckled appearance.

2. The process of claim 1 wherein the heating and dyeing of the fabricare performed simultaneously.

3. A process comprising heating alternate sections of an undrawn linearterephthalate polyester continuous filament at a temperature betweenabout 90 C. and about 115 C., drawing the non-uniformly heated filamentto produce a filament characterized by sharply defined alternate smallerand larger denier segments, the smaller denier segments ranging inlength from about 0.1 to about 1.5 inch, and the larger denier segmentsranging in length from about 0.015 to about 0.15 inch, incorporatingsuch filaments into a fabric, heating the fabric at a temperaturebetween about 90 C. and about 200 C. for between about 30 minutes and 10seconds and dyeing the fabric to impart a novel, speckled appearancethereto.

4. The process of claim 3 wherein the heating and dyeing of the fabricare performed simultaneously.

References Cited by the Examiner UNITED STATES PATENTS 2,278,888 4/42Lewis 2872 2,289,232 7/42 Babcock 287l.3 X 2,296,394 9/42 Meloon 57140 I2,298,071 10/42 Smith l6l9l X 2,465,319 3/49 Whinfield 16l172 2,882,1194/59 Laucius 2874 2,932,850 4/60 McNeill et al 287l.3

MERVIN STEIN, Primary Examiner.

1. A PROCESS COMPRISING HEATING ALTERNATE SECTIONS OF AN UNDRAWNPOLYETHYLENE TEREPHTHALATE CONTINUOUS FILAMENT AT A TEMPERATURE BETWEENABOUT 90*C. AND ABOUT 115*C., DRAWING THE NON-UNIFORMLY HEATED FILAMENTTO PRODUCE A FILAMENT CHARACTERIZED BY SHARPLY DEFINED ALTERNATE SMALLERAND LARGER DENIER SEGMENTS, THE SMALLER DENIER SEGMENTS RANGING INLENGTH FROM ABOUT 0.1 TO ABOUT 1.5 INCHES, AND THE LARGER DENIERSEGMENTS RANGING IN LENGTH FROM ABOUT 0.015 TO ABOUT 0.15 INCH,INCORPORATING SUCH FILAMENTS INTO A FABRIC, HEATING THE FABRIC AT ATEMEPRATURE BETWEEN ABOUT 90*C. AND ABOUT 200*C. FOR BETWEEN